JP2020196177A - Mechanical pencil core and manufacturing method thereof - Google Patents

Abstract

To reduce the deformation of a connection part.SOLUTION: The mechanical pencil core includes a chuck 10 that sandwiches a lead core x by a plurality of claws 11, a clutch 20 that can be annularly fitted and released from the plurality of claws 11, and an advancing/retreating pipe 30 that is annularly connected to a rear end side of the chuck 10. A caulking portion 32 including a recess 32a formed on an outer peripheral surface side and a protrusion 32b formed on an inner peripheral surface side corresponding to the recess 32a is provided on the front end side of the advancing/retreating pipe 30. The caulking portion 32 connects the rear end side of the chuck 10 and the front end side of the advancing/retreating pipe 30.SELECTED DRAWING: Figure 2

Description

The present invention relates to a lead for a mechanical pencil used for a multifunctional writing instrument having a plurality of types of writing instrument functions such as a ballpoint pen and a mechanical pencil, a mechanical pencil having a single writing unit, and a method for manufacturing the same. ..

Conventionally, in this type of invention, for example, as described in Patent Document 1, a chuck whose front end side is divided into a plurality of parts and whose rear end side is formed into a tubular shape, and a chuck whose rear end side is annularly covered. There is a lead for mechanical pencils with a connected tubular joint.
In such a lead for a mechanical pencil, the chuck is formed of a metal material, the joint is formed of a synthetic resin material, and the rear end side of the chuck is press-fitted into the front end side of the joint. The members are connected and fixed.

Japanese Unexamined Patent Publication No. 2014-172377

However, according to the above-mentioned prior art, due to the dimensional accuracy of the joint, deformation at the time of press fitting, etc., the friction between the inner peripheral surface of the joint and the outer peripheral surface of the lead core to be inserted becomes large, or the chuck and the joint The lead core may get caught in a minute step portion generated at the connection point, and the advance of the lead core (falling of the lead core) due to its own weight may be hindered.

In view of such problems, the present invention has the following configurations.
A lead core for a mechanical pencil including a chuck that sandwiches a lead core between a plurality of claws, a clutch that can be fitted and removed in an annular shape on the plurality of claws, and an advancing / retreating tube that is annularly connected to the rear end side of the chuck. In the above, a caulking portion including a recess formed on the outer peripheral surface side and a protrusion formed on the inner peripheral surface side corresponding to the recess is provided on the front end side of the advancing / retreating pipe, and the caulking portion provides the chuck. A lead for a mechanical pencil, characterized in that the rear end side and the front end side of the advancing / retreating pipe are connected.

Since the present invention is configured as described above, the deformation of the connecting portion is reduced, and the lead core is smoothly advanced by its own weight.

It is sectional drawing which shows an example of the core for a mechanical pencil which concerns on this invention. It is an enlarged sectional view of the main part of the core for the mechanical pencil. An example of the receiving member is shown, (a) is a half cross-sectional view, and (b) is a plan view. It is a vertical cross-sectional view which shows the manufacturing procedure of the lead for a mechanical pencil which concerns on this invention in order (a)-(c). It is a vertical cross-sectional view which shows the manufacturing procedure of the lead for a mechanical pencil which concerns on this invention in order (d)-(e).

In this embodiment, the following features are disclosed.
The first feature is a lead core for mechanical pencils, which is a chuck that sandwiches the lead core by a plurality of claws, a clutch that can be fitted and removed in an annular shape on the plurality of claws, and a rear end side of the chuck. In a lead for a mechanical pencil having an advancing / retreating pipe connected in an annular shape, a recess formed on the outer peripheral surface side and a protrusion formed on the inner peripheral surface side corresponding to the recess on the front end side of the advancing / retreating pipe. A caulking portion made of the same is provided, and the rear end side of the chuck and the front end side of the advancing / retreating pipe are connected by the caulking portion (see FIGS. 1 and 2).

As a second feature, a plurality of the caulked portions are provided at intervals in the circumferential direction (see FIG. 2).

The third feature is that a tubular portion is provided on the rear end side of the chuck, a fitting recess that is continuous in an annular shape is provided on the outer peripheral surface of the tubular portion, and the protrusions of the plurality of caulked portions are fitted. It fits into the recess (see FIG. 2).

As a fourth feature, the rear end side of the chuck is connected to the front end side of the advancing / retreating pipe so as to make a slight movement in the radial direction (see FIG. 2).

A fifth feature is a support tube that is formed shorter than the advancing / retreating pipe and is inserted through the front end side of the advancing / retreating pipe and the chuck in a penetrating manner to project the plurality of claws and the clutch forward.
A compression coil spring whose front end is brought into contact with the support pipe and is annularly mounted on the rear side of the advancing / retreating pipe and a compression coil spring in a contracted state are brought into contact with the compression coil spring from the rear side and retracted to the outer periphery of the advancing / retreating pipe. A receiving member that is improperly fitted is provided, and the receiving member is formed in an annular shape having a cut-off portion in a part in the circumferential direction (see FIGS. 1 and 3).

The sixth feature is a method for manufacturing the lead for a mechanical pencil, which includes a caulking step of projecting the advancing / retreating tube from the front end portion of the support tube and forming the caulking portion in the projecting portion (FIG. 4). reference).

The seventh feature is a step of retracting the advancing / retreating pipe after the caulking step, and sequentially mounting the compression coil spring and the receiving member on the rear end side of the advancing / retreating pipe protruding rearward from the support pipe. (See FIG. 5).

<Specific embodiment>
Next, a specific embodiment having the above characteristics will be described in detail with reference to the drawings.

FIG. 1 shows an example of a lead for a mechanical pencil according to the present invention.
The mechanical pencil core 1 includes a chuck 10 for sandwiching and releasing the lead core x by a plurality of claws 11, a clutch 20 that can be annularly fitted and detached from the plurality of claws 11, and a rear end of the clutch 20. The advancing / retreating pipe 30 which is connected to the tubular portion 12 on the side in an annular shape, the support pipe 40 which is formed in a tubular shape shorter than the advancing / retreating pipe 30 and has the advancing / retreating pipe 30 inserted on the rear end side, and the support pipe 40. The tip metal 50 detachably connected to the front end side of the pipe, the lead breaker 60 supported in the tip metal 50, and the front end portion are brought into contact with the rear end of the support pipe 40 to be annular to the rear side of the advancing / retreating pipe 30. It is provided with a compression coil spring 70 mounted on the pipe and a receiving member 80 which is in contact with the contracted compression coil spring 70 from the rear side and is fixed to the outer periphery of the advancing / retreating pipe 30 so as not to be retracted.
The mechanical pencil lead 1 is connected to the front end side of the cylindrical lead tank 90 and is housed in a multifunction writing tool or a mechanical pencil barrel.

A plurality of chucks 10 are formed of an elastically flexible metal material (for example, brass), are arranged concentrically so as to be located around the lead core x, and the front end side is separated in the circumferential direction. A claw portion 11 (for example, about 2 to 4) and a tubular portion 12 for connecting the claw portions 11 in a ring shape on the rear end side are provided. Then, in the claw portion 11, the tubular portion 12 is inserted and fixed to the inner peripheral surface on the front end side of the advancing / retreating pipe 30, and the claw portion 11 moves in and out integrally with the advancing / retreating pipe 30.

The front end side of each claw portion 11 projects outward in the radial direction. Then, the clutch 20 is fitted to the outer peripheral portion of the protruding portion of the plurality of claw portions 11 so as to be disengaged rearward.
The plurality of claw portions 11 grip the lead core x by bending inward in the radial direction, and elastically restore and open to release the lead core x.

The tubular portion 12 is formed in a substantially cylindrical shape. A diameter-expanded portion 12a projecting outward in the radial direction is provided on the latter half side of the tubular portion 12, and a fitting recess 12a1 (see FIG. 2) is provided in the middle of the diameter-expanded portion 12a in the front-rear direction. Be done.

The fitting recess 12a1 contains protrusions 32b of a plurality of caulking portions 32, which will be described later. According to a preferred example of the present embodiment, the fitting recesses 12a1 are formed in a continuous annular shape over the entire circumference, but as another example, a plurality of fitting recesses 12a1 may be provided so as to correspond to a plurality of caulking portions 32, respectively. Is.

The clutch 20 is a cylindrical member having a mortar-shaped inner peripheral surface that expands in diameter toward the front, and is formed of a hard material such as metal. The clutch 20 is supported so as to advance and retreat by a predetermined amount between the step portion 51 in the tip metal 50 and the front end portion of the support pipe 40.
Then, the clutch 20 fits into the plurality of claw portions 11 when moving forward, bends the front portion of the chuck 10 inward in the radial direction, and when the clutch 20 is disengaged from the claw portion 11 rearward, the chuck 10 The front part of the is elastically restored and bent outward in the radial direction.

The advancing / retreating pipe 30 is formed of a metal (for example, brass or the like) into a long cylindrical shape, and its front end side is annularly fitted to the tubular portion 12 on the rear end side of the chuck 10.
On the front end side of the advancing / retreating pipe 30, a fitting cylinder portion 31 formed to be thinner than the rear side is provided. The tubular portion 12 is inserted into the fitting tubular portion 31.
A plurality of caulking portions 32 are formed on the peripheral wall of the fitting cylinder portion 31 at intervals in the circumferential direction.

The front side portion of the advancing / retreating pipe 30 included in the fitting cylinder portion 31 is formed in a substantially cylindrical shape longer than the support pipe 40, and functions as a sliding cylinder portion 33 that slides in contact with the inner surface of the support pipe 40 to advance / retreat.
An annular recess 33a for fitting the receiving member 80 so as not to advance or retreat is provided in the middle of the sliding cylinder portion 33 rearward, and a cylindrical shape having an enlarged diameter further rearward than the sliding cylinder portion 33. The core tank connecting portion 34 is provided.

The caulking portion 32 is arranged corresponding to the front-rear position of the fitting recess 12a1 on the outer peripheral surface of the tubular portion 12 in the chuck 10. The caulking portion 32 is provided on the peripheral wall of the advancing / retreating pipe 30 at a substantially constant interval in the circumferential direction by a dedicated machine provided with a caulking jig or the like at a plurality of points (for example, 3 to 4 locations).
Each caulking portion 32 has a recess 32a formed on the outer peripheral surface of the fitting cylinder portion 31 in the advancing / retreating pipe 30 by pressing a substantially punch-shaped caulking jig, and a fitting cylinder portion corresponding to the fitting recess 12a1. It is composed of a protrusion 32b protruding inward in the radial direction from the inner peripheral surface of 31.

The protrusion 32b fits into the fitting recess 12a1 on the rear end side of the chuck 10. The rear end side of the chuck 10 can be finely moved in the radial direction while being connected to the front end side of the advancing / retreating pipe 30.

To be described in detail, the outer peripheral surface of the enlarged diameter portion 12a of the tubular portion 12 and the inner peripheral surface of the fitting tubular portion 31 are loosely fitted with each other through a minute annular gap s1, and the expanded portion 12 is expanded. An annular gap s2 is secured between the portion in front of the diameter portion 12a and the inner peripheral surface of the fitting cylinder portion 31, and further, an annular gap s3 is also secured between the protrusion 32b and the inner surface of the fitting recess 12a1. Is secured (see Fig. 2).
Therefore, the rear end side of the chuck 10 can be slightly moved in the radial direction with respect to the front end side portion of the advancing / retreating pipe 30, whereby the claw portion 11 on the front end side of the chuck 10 has the vicinity of the caulking portion 32 as a fulcrum. Swinging movement is possible.
Therefore, when the lead core x receives an impact from the chuck 10 due to the gripping operation,
This impact can be mitigated by the fine movement (or the swinging motion) of the chuck 10 to prevent the lead core x from being broken or damaged.

Further, on the rear end side of the core tank connecting portion 34, an annular guide slope 34a whose diameter is gradually reduced toward the rear is provided.
The guide slope 34a facilitates the work of mounting the receiving member 80 described later in an annular shape and the work of mounting the core tank 90 in a ring shape.

The support pipe 40 is formed of a metal material (for example, brass or the like) into a cylindrical shape shorter than the advancing / retreating pipe 30, and is inserted through the front end side of the advancing / retreating pipe 30 and the chuck 10 so as to advance the claw portion 11 and the clutch 20. It protrudes to. The rear end of the clutch 20 is in contact with the front end of the support tube 40.
The inner peripheral surface on the rear end side of the support pipe 40 slides on the outer peripheral surface on the front end side of the advancing / retreating pipe 30 to advance / retreat the advancing / retreating pipe 30.
A tip 50 is fitted and connected to the front end side of the support tube 40 in an annular shape.

The tip 50 is a substantially cylindrical member formed of a hard material such as metal (for example, brass), and is connected to the front end side of the support tube 40 by connecting means such as fitting or screwing (according to the illustrated example). It is detachably connected by (screw).
The front end side of the tip 50 is formed in a tapered shape whose diameter gradually decreases toward the front. The inner peripheral surface of this tapered portion is formed in a cylindrical shape that is in sliding contact with the lead core x.
A core breaker 60 is fitted in the tip 50 on the rear side of the tapered portion and on the front side of the chuck 10 so as not to advance or retreat.

The core breaker 60 is formed in a substantially cylindrical shape from an elastic material such as rubber or an elastomer resin. A conical surface for guiding the lead core x forward is formed on the latter half side of the inner peripheral surface of the core breaker 60, and a cylindrical surface elastically pressed against the lead core x on the front side of the conical surface. Is provided.

The compression coil spring 70 is annularly attached to the advancing / retreating pipe 30, and the front end portion thereof is brought into contact with the rear end portion of the support pipe 40, and the rear end portion is brought into contact with the receiving member 80 described later, so that the support pipe 40 On the other hand, the receiving member 80, the advancing / retreating pipe 30, the chuck 10 and the like are urged rearward.

The receiving member 80 is an annular member having a cut-off portion 81 in a part in the circumferential direction.
To be described in detail, as shown in FIG. 3B, the receiving member 80 is formed in a substantially C-shape in a plan view by providing a cut-off portion 81 in a part in the circumferential direction, and is circumferential from the cut-off portion 81. It has a notch 82 in another portion separated in the direction.

Further, as shown in FIG. 3A, the receiving member 80 is integrally formed of a small diameter portion 80a on the front side and a large diameter portion 80b on the rear side, and is between the small diameter portion 80a and the large diameter portion 80b. It has a step 83.
Then, the receiving member 80 inserts the small diameter portion 80a into the rear end side of the compression coil spring 70, and receives the rear end seat portion of the compression coil spring 70 by the step portion 83.

The cut-off portion 81 is arranged on one side in the radial direction, and is continuous in the axial direction from the small-diameter portion 80a to the large-diameter portion 80b to separate a part of the receiving member 80 in the circumferential direction.
The notch 82 is arranged on the other side in the radial direction so as to face the cut 81, and the inner peripheral surface of the receiving member 80 is notched in a concave shape. To be described in detail, as shown in FIG. 3A, the cutout portion 82 is formed in a concave groove shape continuous in the axial direction on the large diameter portion 80b side and does not straddle the small diameter portion 80a.
The receiving member 80 is integrally molded from a synthetic resin material such as polyacetal (POM).

The receiving member 80 having the above configuration is elastically expanded in diameter and fitted into the annular recess 33a of the advancing / retreating pipe 30 in an annular shape.
To be described in detail, the receiving member 80 is fitted into the advancing / retreating pipe 30 in an annular shape from the rear side, and gradually expands in diameter by sliding in contact with the guide slope 34a on the rear end side of the advancing / retreating pipe 30 and advancing. Further forward, the annular recess 33a is elastically restored, reduced in diameter, and fitted.
When the diameter of the receiving member 80 is increased or decreased as described above, the portion whose cross-sectional area is reduced by the notch 82 (the lower portion of the notch 82 according to FIG. 3B) is mainly formed. , Easily elastically deformed. Therefore, the workability of expanding the diameter of the receiving member 80 and fitting it into the advancing / retreating pipe 30 is good.

Also, the core tank 90. It is a long cylindrical member capable of accommodating a plurality of lead cores x, and is annularly fitted to a core tank connecting portion 34 on the rear end side of the advancing / retreating pipe 30.

Next, a manufacturing method of the mechanical pencil core 1 having the above configuration will be described in detail.
This manufacturing method involves a caulking step (see FIGS. 4A to 4C) in which the advancing / retreating pipe 30 is projected from the front end portion of the support tube 40 and a caulking portion 32 is formed in the protruding portion, and after the caulking step. A step of retracting the advancing / retreating pipe 30 (see FIG. 5D) and a step of sequentially mounting the compression coil spring 70 and the receiving member 80 on the rear end side of the advancing / retreating pipe 30 protruding rearward from the support pipe 40 (see FIG. 5D). (See FIG. 5 (e)).

To explain in detail, first, as shown in FIG. 4A, the sliding cylinder portion 33 on the front side of the advancing / retreating pipe 30 is inserted through the support pipe 40.

On the other hand, the chuck 10 and the clutch 20 are integrally configured in advance.

Next, the rear end portion of the chuck 10 to which the clutch 20 is fitted is connected from the front side to the fitting cylinder portion 31 of the advancing / retreating pipe 30 protruding forward from the support pipe 40.
More specifically, the cylinder portion 12 on the rear end side of the chuck 10 is inserted into the fitting cylinder portion 31, and the peripheral wall of the fitting cylinder portion 31 is crimped by a dedicated machine as shown in FIG. 4 (b). It will be processed.

The dedicated machine includes a plurality of punches arranged at intervals in the circumferential direction, and these punches are moved inward in the radial direction substantially simultaneously to form a plurality of recesses 32a on the outer peripheral surface of the fitting cylinder portion 31, and the same. A plurality of protrusions 32b corresponding to the plurality of recesses 32a are formed on the inner peripheral surface of the fitting cylinder portion 31.

In the above procedure, the plurality of protrusions 32b are fitted into the fitting recesses 12a1 in the tubular portion 12, so that the rear end side of the chuck 10 is connected to the front end side of the advancing / retreating pipe 30 (FIGS. 2 and 4 (FIGS. 2 and 4). c) See)

Next, as shown in FIG. 5D, the advancing / retreating pipe 30 and the chuck 10 are retracted with respect to the support pipe 40 until the clutch 20 comes into contact with the front end of the support pipe 40.

Then, as shown in FIG. 5 (e), the compression coil spring 70 is annularly fitted to the latter half side of the sliding cylinder portion 33 in the advancing / retreating pipe 30, and further, the annular recess on the rear end side of the sliding cylinder portion 33. The receiving member 80 is annularly fitted to 33a.
Therefore, the lead / retreat pipe 30, the chuck 10 and the clutch 20 are urged rearward with respect to the support pipe 40, and the mechanical pencil core 1 is completed.

According to the mechanical pencil core 1 having the above configuration and the manufacturing method thereof, the deformation of the front end side of the advancing / retreating pipe 30 due to the connection of the chuck 10 is smaller than that of the conventional structure.
That is, in the conventional structure, since the rear end portion of the metal chuck is press-fitted into the advancing / retreating pipe (joint) made of synthetic resin material from the front side, the diameter of the front end side of the advancing / retreating pipe (joint) is expanded. It transforms like this. Due to this deformation and variation in dimensional accuracy due to resin molding, the frictional resistance between the lead / retreat pipe (joint) and the lead core x increases, and lead occurs in the minute steps that occur at the connection point between the chuck and the lead / retreat pipe (joint). The lead x may get caught, and the advance of the lead lead (fall of the lead lead) due to its own weight may be hindered.
Further, in the conventional structure, the frictional resistance between the outer peripheral surface of the enlarged advance / retreat pipe (joint) and the inner peripheral surface of the support pipe around it becomes too large, and there is a possibility that the advance / retreat operation of the advance / retreat pipe 30 may be supported. is there.

On the other hand, in the mechanical pencil core 1 of the present embodiment, the advancing / retreating pipe 30 is connected to the rear end side of the chuck 10 by a plurality of caulking portions 32 on the front end side of the advancing / retreating pipe 30 made of a metal material. Deformation on the front end side of the advancing / retreating pipe 30 is suppressed to the minimum necessary.
Therefore, it is possible to prevent the frictional resistance between the advancing / retreating pipe 30 and the lead core x from increasing due to deformation or dimensional variation, or to form a step in the advancing / retreating pipe 30 that causes the lead core x to get caught. .. As a result, the lead core x can be smoothly advanced (falled) by its own weight.
Further, since the front end side of the advancing / retreating pipe 30 is caulked from the outer peripheral side, the front end side of the advancing / retreating pipe 30 is deformed in the diameter expansion direction, and the frictional resistance between the advancing / retreating pipe 30 and the support pipe 40 becomes large. There is no such thing.

In the core 1 for mechanical pencils, as a particularly preferable embodiment, the caulking portions 32 are provided at 2-3 intervals in the circumferential direction, but as another example, the caulking portions 32 are partially provided in the circumferential direction. It is also possible to provide a single number of the caulking portions 32, or to provide four or more caulking portions 32 at intervals in the circumferential direction.

Further, in the core 1 for mechanical pencils, a plurality of substantially dot-shaped caulking portions 32 are provided in the circumferential direction as a particularly good aspect of manufacturability, but as another example, the caulking portions 32 are replaced with a peripheral crimping portion 32. It is also possible to provide an annular caulking portion that is continuous in the direction. In this case, the above-mentioned dedicated machine is replaced with another one, and while rotating the advancing / retreating pipe 30, a jig is pressed against the outer peripheral portion of the rotating advancing / retreating pipe 30 to form a crimped portion in an annular shape. become.

Further, in the above embodiment, the protrusion 32b on the advancing / retreating pipe 30 side is fitted to the fitting recess 12a1 on the rear end side of the chuck 10, but as another example, the fitting recess 12a1 is omitted and the protrusion is projected by caulking. It is also possible to have a mode in which the protrusion 32b is pressed against the outer peripheral surface of the tubular portion 12, or a mode in which the outer peripheral surface of the tubular portion 12 is recessed by pressing the protrusion 32b against the outer peripheral surface of the tubular portion 12.

Further, the present invention is not limited to the above-described embodiment, and can be appropriately changed without changing the gist of the present invention.

1: Mechanical pencil core 10: Chuck 11: Claw 12: Cylinder 12a: Enlarged diameter 12a 1: Fitting recess 20: Clutch 30: Advance / retreat tube 32: Caulking section 32a: Recess 32b: Protrusion 40: Support tube 70 : Compression coil spring 80: Receiving member

Claims (7)

A mechanical pencil core having a chuck that sandwiches the lead core between a plurality of claws, a clutch that can be fitted and removed in an annular shape to the plurality of claws, and an advancing / retreating tube that is annularly connected to the rear end side of the chuck. In
A caulking portion including a recess formed on the outer peripheral surface side and a protrusion formed on the inner peripheral surface side corresponding to the recess is provided on the front end side of the advancing / retreating pipe, and the caulking portion is used to rear the chuck. A lead for a mechanical pencil, characterized in that the end side and the front end side of the advancing / retreating pipe are connected. The core for a mechanical pencil according to claim 1, wherein a plurality of crimped portions are provided at intervals in the circumferential direction. A tubular portion is provided on the rear end side of the chuck, and an annularly continuous fitting recess is provided on the outer peripheral surface of the tubular portion.
The core for a mechanical pencil according to claim 2, wherein the protrusions of the plurality of crimped portions are fitted into the fitting recesses. The lead for a mechanical pencil according to any one of claims 1 to 3, wherein the rear end side of the chuck is connected to the front end side of the advancing / retreating pipe so as to make a slight movement in the radial direction. A support tube formed shorter than the advancing / retreating pipe and penetrating the front end side of the advancing / retreating pipe and the chuck to project the plurality of claws and the clutch forward.
A compression coil spring whose front end is brought into contact with the support pipe and is annularly mounted on the rear side of the advancing / retreating pipe.
A receiving member that is in contact with the compressed coil spring in the contracted state from the rear side and is fitted to the outer periphery of the advancing / retreating pipe so as not to be retracted is provided.
The lead for a mechanical pencil according to any one of claims 1 to 4, wherein the receiving member is formed in an annular shape having a cut-off portion in a part in the circumferential direction. The method for manufacturing a lead for a mechanical pencil according to claim 5, further comprising a caulking step of projecting the advancing / retreating pipe from the front end portion of the support pipe and forming the caulking portion in the protruding portion. After the caulking step, the step of retracting the advancing / retreating pipe and the step of sequentially mounting the compression coil spring and the receiving member on the rear end side of the advancing / retreating pipe protruding rearward from the support pipe are included. 6. The method for manufacturing a lead for a mechanical pencil according to claim 6.

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